A woman was last night being cared for by social services in Sicily after losing her home and her job for collaborating with police against an alleged rapist, in a case highlighting pernicious local notions of "honour" and loyalty.

The woman, who has not been named, was sacked by her employer and evicted from her house by her brother, despite the fact that her assistance was instrumental in bringing criminal charges against an alleged murderer.

The affair is a reminder of the persistence in parts of southern Italy of age-old concepts of honour and a prejudice against helping the authorities that, among other things, allowed the Mafia's "boss of bosses", the recently arrested Bernardo Provenzano, to remain at large for more than four decades.

At the end of last month the 38-year-old woman was asleep in the house she shared with her brother when she was attacked by an intruder who had climbed in from a balcony.

She fled to a bathroom, but her attacker kicked in the door. By then, however, he and his intended victim had made so much noise that neighbours appeared in the street and on terraces to see what was going on.

After punching the woman hard in the face the man fled.

When the Carabinieri got to the house they found her slumped in a corner clutching a clump of her attacker's hair. She gave investigators a detailed account of what happened, and the hair provided them with vital forensic evidence, allowing a later DNA match.

It was not long before they visited Emilio Zanini, 42, a local man who was awaiting trial on charges of attempted rape. As they searched his home they found newspaper reports of a deadly attack last year on a university student.

Roberta Riina, 22, was found with a crushed skull. After a sample of his DNA was matched with one found at the scene of the killing Zanini was charged with the student's rape and murder.

Back in Partinico, a stronghold of the Mafia, the woman victim had been dismissed from her part-time job as a cleaner in a bar.

Police told Italian media it was not clear whether her employer was concerned about reprisals or simply enforcing "omerta", the tradition of non-cooperation with the police that not only binds mafiosi but is also respected by many other Sicilians.

Last Wednesday the woman's plight took a further turn for the worse when she was thrown out of the house that she and her brother inherited from their parents. The council has since arranged for her to be taken into a hostel.

Mimma Tortorici, the head of local social services, told the daily newspaper Corriere della Sera: "This is typical of the attitude of a brother who decides to take 'playing the Sicilian' to its ultimate conclusion so as to remove the shame [of an attempted rape]."

The paper quoted the mayor of Partinico, Giuseppe Montinisi, as saying he was trying to arrange for the woman to be given a job at the council.

The case has also raised questions about why Zanini was free at the time of the alleged offences. Three years ago he was accused of attempting to rape his grandmother, who was 81.

Following Zanini's arrest the then commanding officer of the local detachment of the Carabinieri, Italy's paramilitary police, wrote a report describing him as a "very dangerous individual, capable of any sort of offence".

He specifically requested that the judge dealing with the case in Palermo should take steps to ensure that the accused man was remanded in custody while he awaited trial.